const {
    stripScript,
    stripTemplate,
    genInlineComponentText
} = require('./util')
const md = require('./config')

module.exports = function(source) {
    const content = md.render(source)

    const startTag = '<!--element-demo:'
    const startTagLen = startTag.length
    const endTag = ':element-demo-->'
    const endTagLen = endTag.length

    let componenetsString = ''
    let id = 0 // demo 的 id
    let output = [] // 输出的内容
    let start = 0 // 字符串开始位置

    let commentStart = content.indexOf(startTag)
    let commentEnd = content.indexOf(endTag, commentStart + startTagLen)
    while (commentStart !== -1 && commentEnd !== -1) {
        output.push(content.slice(start, commentStart))

        const commentContent = content.slice(commentStart + startTagLen, commentEnd)
        const html = stripTemplate(commentContent)
        const script = stripScript(commentContent)
        let demoComponentContent = genInlineComponentText(html, script)
        const demoComponentName = `element-demo${id}`
        output.push(`<${demoComponentName} slot="source" />`)
        componenetsString += `${JSON.stringify(demoComponentName)}: ${demoComponentContent},`

        // 重新计算下一次的位置
        id++
        start = commentEnd + endTagLen
        commentStart = content.indexOf(startTag, start)
        commentEnd = content.indexOf(endTag, commentStart + startTagLen)
    }

    // 仅允许在 demo 不存在时，才可以在 Markdown 中写 script 标签
    // todo: 优化这段逻辑
    let pageScript = ''
    if (componenetsString) {
        pageScript = `<script>
      export default {
        name: 'component-doc',
        components: {
          ${componenetsString}
        }
      }
    </script>`
    } else if (content.indexOf('<script>') === 0) { // 硬编码，有待改善
        start = content.indexOf('</script>') + '</script>'.length
        pageScript = content.slice(0, start)
    }

    output.push(content.slice(start))
    return `
    <template>
      <section class="content element-doc">
        ${output.join('')}
      </section>
    </template>
    ${pageScript}
  `
}
